1. Field of the Invention
This invention relates to a synthetic resin thin wall container and, more particularly, it relates to a synthetic resin thin wall container that is reinforced but easily crushable and has an improved profile at the neck, body and bottom.
2. Related Background Art
In recent years, it has been encouraged to save plastic materials for molded products and recycle plastic products from the viewpoint of environmental protection. Efforts have been paid to provide thin wall containers so that waste containers may be crushed and collected. Thin wall containers that can be easily crushed by hand are already well known.
However, a known thin wall container weighs 0.065 g/ml for every 1 ml of the liquid contained therein if the container is made of polypropylene (PP). In other words, resin has to be used by 32.5 g to form a container with a capacity for containing 500 ml of liquid. If the container is made to weigh less than 0.05 g/ml for every 1 ml of the liquid contained therein by reducing the wall thickness, it is highly difficult for the container to maintain its shape.
Additionally, there arises a problem that, if the wall thickness of the body portion of the container is reduced, the body loses, if partly, its rigidity and buckling strength. If the wall thickness of the peripheral wall of the container bottom extending from the body portion is also reduced, the bottom can easily become deformed and/or give rise to cracks when the container is dropped and subjected to impact. The buckling strength of the bottom of the container is also reduced as a function of the reduction of the bottom wall thickness.
Then, the net result will be that, when the container is filled with liquid, the container body portion becomes deformed and/or the peripheral wall of the container bottom is buckled so that the container will no longer be able to stand upright.
Furthermore, if the body portion of a blow molded container has an elliptic cross section, adjacent containers that are being transferred from a work station to another can contact each other along a line at the sides of its major axis. Then, containers can become deformed as a result of collision.
Still additionally, as a result of line contact, containers can become displaced relative to each other and stand obliquely relative to the moving direction to consequently give rise to various problems.
Various problems also arise when blow molded containers are moved from a work station to another if the wall thickness of the shoulder portion is reduced unless the neck portion is improved and/or reinforced. Such improvement and/or reinforcement is also necessary in order to reliably close the neck with a cap after filling the container with liquid.
There also arises a problem that the container Cannot be grasped by hand with the neck ring thereof in use. Finally, it is highly difficult to close the container with the cap while holding it with hand because the shoulder portion has a thin wall thickness.
In view of the above pointed out circumstances, it is an object of the present invention to provide a synthetic resin thin wall container that can be formed with a reduced amount of resin material and is provided with reinforcing ribs at relevant positions in the body and bottom to make it able to maintain its shape while it can be crushed by hand with ease.
Another object of the present invention is to provide a thin wall container having a reinforced neck so that the container can be reliably opened and closed by holding the cap with hand.
According to the invention, the above objects and other objects are achieved by providing a synthetic resin thin wall container having a flattend cross section, wherein a body comprises front and rear walls and side walls. In order to reeinforce the body, each of the front and rear walls is provided with transversally extending reinforcing ribs and has an elliptical cross section. Each of the side walls is a vertical plane which intersects the elliptic cross section of the front and rear walls, and is provided with a plurality of reinforcement. The reinforcement is recesses arranged vertically at regular intervals.
Each or both of the front and rear walls is provided with a plurality of transversally extending recesses having an arcuate cross section, to make the wall surface corrugated.
In order to reinforce the bottom, the bottom comprises a peripheral wall connected to the body, and a bottom wall. The peripheral wall is inclined by a predetermined angle, and provided with a reinforcing rib
The reinforcing rib of the bottom is an upper lateral rib provided between the body and the bottom, a lower lateral rib provided at a lower end of the peripheral wall, and/or vertical ribs arranged at regular intervals, or these combinations.
The lower lateral ribs and/or each of the longitudinal ribs has a substantially vertical lower wall.
In order to reinforce the neck, and in order to make opening of the cap easy, the neck has a holder ring or a neck ring with knurl, and a lower cylindrical neck section has a predetermined height so as to be held by a thumb and fingers.
In order to reduce the amount of the material, and in order to obtain a thick wall container, a container is preferably formed by blow molding, using PP resin by 0.015 to 0.05 g/ml or PE resin by 0.021 to 0.07 g/ml (weight of the resin per the volume of the liquid content).